Bohr’s model of the atom
Neil Bohr in 1913 observed that basic features of Rutherford’s atomic model namely presence of nucleus and revolving electrons were correct but that the electrons revolved round the nucleus in certain allowed circular orbits and that the electrons did not radiate and therefore its energy remained constant. However, the electron could jump from outer stationary orbit to inner orbit and while doing so emits radiation equal to the difference in energies corresponding to the two orbits.
Drawbacks of Bohr’s theory:
1 – On careful analysis of hydrogen spectrum it was observed that a single line in any hydrogen series actually consisted of two or more single lines with very close wavelengths. The fine structure of hydrogen spectrum could not be explained by Bohr’s theory.
2 – It could not explain relative intensity of different spectral lines.
3 – It is observed that when an electric or magnetic field is applied to the atom. each spectral line splits into several lines. The former effect known as stark effect and the later effect known as Zeeman effect could not be explained by Bohr’s theory.
4 – Bohr’s atomic model could not explain the distribution and arrangement of electrons in an atom.
